The inner circuit structure of the current source driver adopted in an electrophoretic display apparatus generally comprises a plurality of control circuits corresponding to the number of the source lines. For the common electrode above the electrophoretic film and biased by a DC voltage (i.e., DC-common), the pixel potential should have three levels, that is, high level, low level, and common level. The three levels are respectively used to move particles upward, to move particles downward and to hold particles at the same position. Therefore, two-bit data is needed. Because each of the control circuits must receive the image data with the two bits, each of the control circuits must use two same circuits to process the image data with the two bits, and each of the control circuits further comprises an additional decoding circuit to decode the image data with the two bits. Therefore, in the condition of having a plurality of pins, the circuit of the conventional source driver is very complex, and the size of the circuit of the source driver is very large. Furthermore, the width of the outer frame of the display panel is determined by the size of the source driver (which is more complex than the gate driver), thus it is difficult to reduce the width of the outer frame of the display panel because the source driver is very complex, and it goes against the trend of narrowing the frame of the display panel.